Staff warned the supervisors this week that storage levels at Lake Mendocino remain critically low — just 46.7 percent of normal capacity to serve cities from Healdsburg north — and worrisome at the much larger Lake Sonoma, just short of 73 percent, or about a year's worth of water before the Sonoma County Water Agency would be forced to impose rationing on cities from Windsor south.

"Despite the rain we've had in February and March, it doesn't look like we're going to get enough relief to get us out of the drought," county Emergency Manager Chris Helgren told supervisors.

Cities north of Lake Sonoma are under mandatory conservation measures, while cities south are being asked to cut consumption by at least 20 percent through the summer to stall mandatory measures as long as possible.